The small coastal town of Lynmouth became known throughout the world for the disaster that struck in August 1952. On the night of the 15th, after continuous rain throughout the day, the East and West Lyn Rivers rose suddenly and filled with the waters from their Exmoor catchment. Large boulders and rocks were carried in the flow towards the village, destroying houses, roads and bridges. Many lost their lives during that dark and terrifying night. The whole of Exmoor was affected and considerable damage was caused on the Barle, Exe, Heddon and Bray but the worst effects were at Lynmouth. This is because the water draining from most of the northern side of Exmoor ends up in the East and West Lyn Rivers, which join at Lynmouth. Hundreds of thousands of years ago these rivers used to run to the sea much further to the west but during the Ice Age the side of their valley was eroded by the sea and, as a result, they fell to the sea along a much shorter and steeper course. This makes the waters descending on Lynmouth particularly fast and erosive.

Although not the biggest flood Britain has had, it was one of the most spectacular and most studied. Interest was shown in the small scale as well as the larger effects on the landscape. Green studied the effects on river courses, erosion and deposition and Gifford and Kidson studied landslipping and its causes in the upper reaches of the Exe. Whilst it is still possible to see landforms created by the flood and to calculate its flow from remaining flood channels, most of the evidence of the flood has now disappeared, although parts of the West Lyn - the Glen Lyn gorge and part of the headwaters near Woolhanger - are now a geological Site of Special Scientific Interest for the evidence they show of the flood. At first it seemed that the flood confirmed the theory that most of the shaping of our landscape occurred during such violent events that were perhaps hundreds of years apart. However, work by Anderson and Calver on how the great scars and piles of boulders left by the flood have largely been removed by commonplace fluvial activity has changed our view of the shaping of landscape. Few now remember the disaster but its study has had far reaching effects upon our understanding of erosion and the way we deal with floods.

Evidence of Previous Floods

Observations made following the disaster suggested that past floods had occurred at greater magnitudes, although their dates, numbers and frequencies are unknown. The alluvial deposits of banded loam, gravel and boulders all around Lynmouth are indicators of past floods. The 1952 flood had caused erosion of the river bed and exposed in the banks boulders of huge size, whose outline gave proof that they had been rolled there by a larger volume of water. Until erosion had exposed them they had rested under layers of smaller debris and a cover of soil and vegetation including old oak trees. The age of the covering was no doubt considerable, pointing to long recurrence intervals between these heavy floods (Dobbie and Wolf, 1953; Green, 1955). There was an account of a devastating flood in 1770, when it was written:

"The river at Lynmouth by the late rain rose to such a degree as was never known by the memory of any man now living, which brought down great rocks of several tons each, and choked up the harbour. And also carried away the foundation under the Kay on that side of the river six foot down and ninety foot long, and some places two foot under the Kay, which stands now in great danger of falling."

It is possible that this flood was responsible for the deposit of boulders mentioned above. An even more devastating flood was mentioned in 1607 but this appears to have been more of a tidal surge or tsunami than a river flood. Further flooding has been reported numerous times since 1952. In 1978 Watersmeet was evacuated. In 1982 snow melt and heavy rains caused the boulders of the West Lyn to start moving again, and heavy rains in 1990 caused further concerns. Bad flooding has occurred in Barbrook four times since 1952.

The Passage of the Waters

The following is an account from writer S H Burton:

"Lynmouth. The vast downpour that descended on the Chains was refused by the waterlogged, impervious land. Down every gully and natural depression, down the channels dug by John Knight, down the northwards running combes, the thousands of tons of water flowed into the East and West Lyn rivers. Farley Water and Hoaroak Water joined the already swollen East Lyn at Watersmeet. Half a dozen streams converging at the head waters of the West Lyn brought the deluge from the western Chains, and at Barbrook Mill another influx from Woolhanger Common joined the raging torrent, sweeping bridges and houses away before starting the last deadly descent into Lynmouth", (Burton, 1952. 335).

Much has been written on the human impact of the flood and this can be researched at the Flood Memorial Hall and Glen Lyn Gorge at Lynmouth. The damage and loss of life was at the time the subject of the media, for which the national impact from such a tragic occurrence aroused extraordinary interest. In his article 'Unparalleled Scene of Destruction, A. J. Butcher wrote in The Western Morning News the following Monday:

"Superlatives are too puny to describe the calamity, which has befallen Lynmouth and Barbrook. Deaths on a wartime scale, destruction at Barbrook worse than in the heaviest blitz, hundreds of residents and visitors personally ruined and destitute - the story stuns the human mind".

The Sunday Express also reported the incident and published eye witness accounts from guests staying in the Lyndale Hotel, Mr H. L. Watson of Catford who was staying in the hotel with his wife and family said:

"From seven o'clock last night the waters rose rapidly and at nine o'clock it was just like an avalanche coming through our hotel, bringing down boulders from the hills and breaking down walls, doors and windows. Within half an hour the guests had evacuated the ground floor. In another ten minutes the second floor was covered, and then we made for the top floor where we spent the night".

Arthur Brooks of Croydon was also staying in the Lyndale hotel and reported:

"We were looking out when we saw three people being washed out to sea. We managed to get a hold of them and brought them through the window. By the morning boulders were piled 20ft high outside that window".

After the Rains had Stopped

Once the flood had subsided the full extent of damage, both erosional and depositional, could be assessed. Trees stripped of their bark were intermingled with enormous piles of boulders and occasionally interspersed was the wreckage of human habitation and property. River banks had been ripped out, exposing dangling roots; walls and hedges were left with gaps torn through; potholes had been gauged out of the ground leaving bewildered trout swimming in them (Green, 1955).

The river course had been altered, shortening the length by cutting through meanders. In places flood water was forced out of the constricted river bed and cut back from the banks where it re-entered the channel until the blocked channel was completely bypassed. Following the constrictions where the valley opened out and the gradient slackened, boulder deposits were found. Yet on most of the rivers the gradient was so high and the flood plains so narrow that minimal storage could be achieved. The size of the individual boulders shifted depended upon the availability of boulder material and the water velocity to shift them. The largest moved was of some 350 cu. ft. found in the West Lyn, while the East Lyn produced smaller and more rounded material. Peat was eroded from the headwaters of the valley as the waters undercut the already saturated ground, causing land slips of peat up to 40 ft by 18 ft by 5 ft thick to be carried floating or rolling several hundreds of yards downstream. Gouging of the ground downstream from breaches in stone walls resulted in pits of between 2 and 8 feet deep. Similar gouging caused the undermining of bridges on their upstream side, as waters were forced down and underneath the arches removing the drift material supporting the bridge piers. Potholes caused by trenching measured to depths of 12 ft as surface water moved downwards in sheets, entrenching itself in ruts and then rapidly downcutting. Slipping occurred in the drift deposits overlying the Devonian rock, as water ran over the impermeable layer, sweeping away up to two foot of the saturated drift and further inducing slumping. The two small reservoirs at Woolhanger and North Furzehill, both on West Lyn tributaries, burst. Suggestions that these may have been an important contribution to the flood disaster have been discredited as all the debris from the burst was deposited some 200 yards downstream with little damage to the valley below (Green, 1955).

During the period that followed the flood disaster it became noticeable that rainfall of unusual intensity caused a very rapid rise in the river levels. This immediate increase in run-off level prior to the flood was originally attributed to the effects of exhaustion of water retention within the soils. Subsequently it became evident that this situation was more permanent in that there had been an improvement in the discharge pattern of the whole catchment basin with scouring of new tributaries and widening of the channel (Dobbie and Wolf, 1953). The flood's devastating effects upon buildings and bridges occurred in two ways:

Firstly, direct battery was accomplished by the sheer weight of the flood waters and its load of trees and boulders pounding against the artificial structures. The main street of Lynmouth was damaged in this way, as was the bridge at Glebe House, Malmsmead, where both its piers were based on the solid Devonian rock and could stand the weight of debris and water behind. There the bridge broke at its weakest point, the junction of the span and the sides.

The second way of property destruction was the undermining of structures that were built on easily erodable drift deposits. Most of the ruination of houses and bridges was due to this undermining action (Green, 1955).

The following examples given by Green illustrate this point:

Lyn Bridge (West Lyn River) A packhorse bridge of traditional construction. The archway of 75 sq. ft opening was obviously inadequate to take the water flow of about 750 sq. ft cross section area, and the parts based on the solid Lynton Beds held but those based on drift were destroyed.

Hillsford Bridge (Farley Water) The bridge was completely inadequate to take the great volume of water, trees and boulders but the foundations based on solid rock resisted erosion whilst those based on drift were swept away.

Barbrook (West Lyn) Houses built on drift were undercut and fell into the river.

Countisbury Hill Bridge (East Lyn) The retaining wall on the downstream side of the bridge was removed and on the upstream side was weakened by the washing out of its support from behind through a small break in it.

The damage at Lynmouth itself was predominately to the newer constructions, built during the Victorian era when the area grew in popularity. Due to the restricted nature of the site, many buildings were built out into the former course of the Lyn, which was diverted into a confined channel. During the flood the river attempted to revert to its former, more direct, course and widen its channel, resulting in the destruction of houses and bridges. Although a large amount of debris was carried out to sea, a considerable amount was deposited on the river beds, which were raised from 6ft to 10ft above their original levels (Carnegie, 1956). The bridge over the West Lyn, an immensely solid structure based on the Lynton Beds, did not give way to the waters. Instead, the area below filled with flood debris and thereafter acted as an obstacle, diverting the West Lyn and its debris load down the main street of Lynmouth. Meanwhile, the East Lyn had removed the easily erodable alluvial deposits at its bankside, undermining the cottages of Middleham and depositing them into the flow (Green, 1955).

"The valley form of the lower reaches is a V-shaped gorge, so narrow at the bottom that there is no room for a road beside the river. The valley sides are too steep for cultivation and are clothed with oak woods, with here and there a cliff of naked rock. There is no room in these valleys for a village and no call for one because the arable land lies several hundred feet above the their floor. The single exception is Lynmouth which originated as a fishing village and developed as a resort. But even here, at the river mouth, there has only been room to build on the river bed itself, as has been proved by the flood which washed away so many houses merely by claiming for itself again the boulder beds on which they had been built". (Scott Simpson, 1953, cited in Dobbie and Wolf, 1953)".